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Well I tuned a buddies STi with an unported wastegate and found he holds boost easier and for a lot longer in the RPM range.

So now I'm going to swap out my ported exhaust housing on my 39 with an unported....I know I'm going to have to completely retune so my question is...should I leave the boost numbers the same do you think and just mess with the boost gain? Or do you think I will have to decrease the numbers as the RPM's increase?

I decreased the boost number as the RPMS increase and he didn't seem to get creep but the boost didn't taper off much in 5th. I tuned it for about 1.3 bar and it was still holding around 1.3 bar when I let off around 5500 in 5th gear. that makes me nevervous as I know the turbo is really pushing too much and the IDC was not doing so hot.

Is there a way to tune this problem out without dramatically affecting the performance of the lower gears? Does anyone have an example boost map setup for an unported wastegate and also could you tell me what the boost gain was?

Yeah I know mine is going to be different but a template would help significantly...

I simply smoothed the ramp where the wastegate flows out towards the hole, just as it was shown on here but I am an obsessive compulsive piece of crap and I just had to have it completely 100% smooth...not so much as a ripple in the transition so I'm sure flow is amazing. I also ported the exhaust side of the turbine hole a hair to try and combat any over-porting of the wastegate....figured it would allow faster flow through the turbine by a bit..guess not.

It's not THAT bad.

I hit 19psi (with a higher boost number and boost gain than everyone else) but I can't flow more than 12.5 to redline.

I used the same map on my buddies unported STi (only had to modify boost map and gain) and he held 19 easy to about 5000 and then slowly dropped to about 15 psi. I was envious.

We did a pull next to each other and were near identical but he pulled about a 1/2 car to 5th gear. I have one more mod though so I should have beat him.....header.

I just want to be able to hold boost for longer. My top end just falls off too much.

I tried the "helper spring" an it was pretty badas but it was inconsistent. I help 14 psi to redline but I couldn't get it to keep the same boost on spoolup...kept spiking way too high.

I've e-mailed deadbolt too because I've heard they are coming out with a stiffer wastegate actuator spring and they've also solved some low boost problems with a different restrictor pill. If either of those two things helps I'd rather do that because then I'd know for sure I wouldn't creep.

So you're not creeping. Your wastegate is blowing open. Different (opposite) problem. A manual boost controller might help, because it can ensure that the only pressure on the wastegate arm (while you're under your target boost) is from the exhaust itself. If an MBC doesn't allow you to hold boost, then you're hosed. You need a stiffer wastegate spring to keep it from blowing open. If the MBC helps, you may want to run a serial MBC along with your factory boost control solenoid. That's what I use. The MBC keeps all pressure off the wastegate below a set minimum pressure, and the factory bleeder allows me to run higher boost from there, with lower values in my boost map (lower duty cycles from the solenoid).

My wastegate still blows open, but not until later. I'm too lazy to get a helper spring

Boost creep is when the boost goes higher then desired, so I guess boost creep isn't the problem since your boost is going lower then desired. Try openning the abc a bit. If that doesn't work, get a bigger turbo.

I have no creep right now. I know this but I've got the chance to swap out my ported exhaust housing for an unported....meaning I WILL have creep...and was curious to know if I do this...would it be possible for me to tune it out...

I just want to hold more boost but if it comes at the expense of me never being able to get rid of creep then I'll stick with my current housing.

I'm hoping that maybe a restrictor pill or stiffer wastegate spring would help too..that way I can keep my ported housing and still hold the boost I want. My problem is right now the wastegate opens and the flow is so great I can't get it to close back enough to allow me to hold boost. I can put gain down to zero, open the ABC fully, and run 500 for the boost number from 5k on up and still not push more than 12.5 to redline. The wastegate spring just can't pull the gate shut.

A ported wastegate shouldn't stop you from holding the same amount of boost as an unported one as long as the port is smaller then the wastegate flapper. The only thing it should do is make the boost controll better........

A ported wastegate shouldn't stop you from holding the same amount of boost as an unported one as long as the port is smaller then the wastegate flapper. The only thing it should do is make the boost controll better........

peace

Actually, think of it in terms of fluid dynamics. before the porting the air had a straight passage through the spiral of the exhaust housing. After the porting it now has a smooth bypass out the wastegate.

When the boost increases and begins to open the wastegate, now that the flow is much better the air rushes through the wastegate much faster because is so easy to flow through. This causes the user (me in this case) to have to decrease the pressure to the wastegate so it will remain closed for longer to achieve a higher peak boost.

Now that the gate is opened and the peak boost has been hit it's up to the spring pressure of the wastegate actuator to be able to hold the gate open the proper distance to keep the proper boost level. Well the flow is so great through the hole the gate cannot close enough and so the flow is so fast the turbo just can't keep spinning as fast so the boost drops.

This is why adding the "helper spring" increased my peak boost as well as my ability to hold boost to redline. But because the spring I bought wasn't designed to do what I'm having it do...the heat from the turbo (i think) is causing the spring to loosen up after warming up and thus my boost is uber high when it's cold and quite a bit lower when warm. Just not happy with that "ghetto" kind of performance.

I'm hoping that maybe a restrictor pill or stiffer wastegate spring would help too..that way I can keep my ported housing and still hold the boost I want. My problem is right now the wastegate opens and the flow is so great I can't get it to close back enough to allow me to hold boost. I can put gain down to zero, open the ABC fully, and run 500 for the boost number from 5k on up and still not push more than 12.5 to redline. The wastegate spring just can't pull the gate shut.

So like I said, give an MBC a try. Or, if your wastegate is blowing open early enough, disconnect the hose from the wastegate actuator (but be VERY CAREFUL if you do this, because boost will spike). See if that helps. If it doesn't help, you need either a stiffer wastegate spring or a less flow-happy housing.

Personally, I would try the wastegate helper spring again and just see if you can smooth it out. You may want to try the serial MBC. It should help keep things stabilized by keeping any pressure off the wastegate actuator.

A ported wastegate shouldn't stop you from holding the same amount of boost as an unported one as long as the port is smaller then the wastegate flapper. The only thing it should do is make the boost controll better........

peace

Actually, you've got a certain backpressure pushing on the flapper. If you enlarge the port, there's more surface area that the same pressure is pushing on, meaning more overall force acting on the spring. So it will blow open. If you don't touch the port at all, it shouldn't have any effect until it first opens - and then fluid dynamics would come into play, potentially keeping it open longer.

FWIW, I never ported my VF39 and never had an issue with creep. I had a catless turboback (TXS) and ran high boost as early in the RPM range as possible, even in cold weather, so I did pretty much everything I could to get creep, and it still had perfect boost control. There's a lot of production variance in the turbos.

So if you don't mind the possibility of creeping and needing to pop the turbo off later to port it, you may want to just stick the unported housing on and see how it does.

FWIW, I never ported my VF39 and never had an issue with creep. I had a catless turboback (TXS) and ran high boost as early in the RPM range as possible, even in cold weather, so I did pretty much everything I could to get creep, and it still had perfect boost control. There's a lot of production variance in the turbos.

So if you don't mind the possibility of creeping and needing to pop the turbo off later to port it, you may want to just stick the unported housing on and see how it does.

Yeah I originally tried to see if I would get creep and I got it bad with my turbo back. 4th gear even would creep....of course the highest it ever got to was 1.36 bar....which right now wouldn't be that bad since my map is tuned for 19.5 psi...but regardless I would feel better touching up the port just a hair...couldn't possibly be as much boost loss as I'm losing now.

Have you tried running bigger bleedoff lines to your FBC and then out to the turbo inlet pipe? The FBC can accomodate bigger lines. I adapted my small wastegate tubing to bigger (maybe 1/4" ID) plumbing at the T , then kept it big all the way to the FBC and out to it's vent to atmosphere. This lets the FBC bleedoff more pressure. It might help your wastegate "catch back up" after it opens. If you currently have little spike, maybe you could just lower the gain and try to keep the control of the wastegate a little more gradual.

Have you tried running bigger bleedoff lines to your FBC and then out to the turbo inlet pipe? The FBC can accomodate bigger lines. I adapted my small wastegate tubing to bigger (maybe 1/4" ID) plumbing at the T , then kept it big all the way to the FBC and out to it's vent to atmosphere. This lets the FBC bleedoff more pressure. It might help your wastegate "catch back up" after it opens. If you currently have little spike, maybe you could just lower the gain and try to keep the control of the wastegate a little more gradual.

And do you still have the restrictor pill in there?

The ABC is out two turns. The problem is not in hitting the peak boost. That's really the only function any of these things will help with.

Once the peak boost is hit my wastegate is staying open because the spring cannot pull the gate back shut and this is why the boost is tapering.

Once the boost is lower than the set target boost decreasing the pressure flowing to the actuator isn't going to help since it should already be cut off since the boost selenoid isn't seeing the boost that it wants.

And FYI lowering the gain will cause more boost spiking not less....but currently I don't have spike. I hit my target boost dead on but instantly after hitting my target boost I lose boost dramatically.

Yeah. That is annoying. Mine looked like that. I've been trying to nail down why I got it back. I ran a greddy profec B, the TurboXS dual stage MBC inline with the Profec. The AVC-R and all the time switching these setups back and forth with the UTEC and the EBC. That last time I webnt back to the UTEC (and played with the maps I'd used before) it decided to hit boost and stick with it. I'm kinda confused as to why, but I'm not looking a gift horse in the mouth. I'm also not messing with it anymore, as far as the equipment goes.

And I know the lower gain will spike. I'd just try it out a little to see. My wording is weird when I post too early in the morning.